Reviews the REA model method for designing AIS.
What is an REA model? The REA model contains resources, events, agents and now locations and is used to design accounting systems that can be integrated with other enterprise data. This is a power point presentation by William E. McCarthy. http://www.msu.edu/user/mccarth4/cookie--elmo--basic%20REA.ppt It describes the REA model using Elmo and the cookie monster.
Possible item for discussion, this claim made by the ever-popular Wikipedia
REA is a popular model in teaching accounting information systems (AIS). But it is rare in business practice--companies cannot easily dismantle their legacy systems to meet REA's radical demands.
The following definitions are from a website titled REA Technology:
Economic Resource is a thing that is scarce, and has utility for economic agents, and is something users of business applications want to plan, monitor, and control. Examples of economic resources are products and services, money, raw materials, labor, tools, and services the enterprise uses. Economic Agent is an individual or organization capable of having control over economic resources, and transferring or receiving the control to or from other individuals or organizations. Examples of economic agents are customers, vendors, employees, and enterprises. Economic Event represents either an increment or a decrement in the value of economic resources that are under the control of the enterprise. Some economic events occur instantaneously, such as sales of goods; some occur over time, such as rentals, labor acquisition, and provision and use of services. (http://reatechnology.com/)
How is the REA model of benefit to AIS designers and developers?
Entities: Anything in which we are interested that exists independently.
Attributes: An item of data that characterizes an entity or relationships. It describes the entity or relationship
Relationships: The assocation between entities. The relationships must be defined well in order to extract information from the database
Types of Relationships:These include 1:1 (one to one), 1:N (one to many), and M:N (many to many)
Relationships:
Unary - a relationship between instances of the same entity.
Binary - a relationship between instances of two entities.
Ternary - a relationship between instances of three entities.
Cardinality - degree of maximum participation in a relationship
Optionality - (participation constraint) degree of minimum participation in a relationship
Relational Database Concepts and Definitions:
relation - (table for an entity) a set of data representing one or more occurrences of a resource, event or agent.
tuple - (row of a table) a set of data that describes a single instance.
attribute - (column or "field") a type of data that characterizes an entity.
referential integrity - for every attribute value in a relation that references another relation, the referenced row must remain intact.
Mapping the REA model to a Relational Database (discuss the steps):
Mapping the REA model to a Relational Database (discuss the steps):
1. Create a separate relational table for each entity: the logical starting point - specify the database schema before expansion of the relation to account for specific tuples. Steps 2 and 3 are needed to complete the schema
2. Determine primary key: uniquely identifies any row within the table.
3. Determine the attributes for each of the entities
4. Implement the relationships among the entities by ensuring that the primary key in one table also exists as an attribute in every table for which there is a relationship specified in the REA diagram: referential integrity must be considered in this step. One to one relationships may start at either table. Many to many relationships must implemented by starting with a primary key that is a composite of the primary keys of the relations that are being linked. One to many relationships are implemented by including the primary key of the table on the one side of the relationship as an attribute in the table on the many side of the relationship.
5. Determine the attributes, if any, for each of the relationship tables.
REA Model:
Reviews the REA model method for designing AIS.What is an REA model? The REA model contains resources, events, agents and now locations and is used to design accounting systems that can be integrated with other enterprise data. This is a power point presentation by William E. McCarthy. http://www.msu.edu/user/mccarth4/cookie--elmo--basic%20REA.ppt It describes the REA model using Elmo and the cookie monster.
Possible item for discussion, this claim made by the ever-popular Wikipedia
REA is a popular model in teaching accounting information systems (AIS). But it is rare in business practice--companies cannot easily dismantle their legacy systems to meet REA's radical demands.
The following definitions are from a website titled REA Technology:
Economic Resource is a thing that is scarce, and has utility for economic agents, and is something users of business applications want to plan, monitor, and control. Examples of economic resources are products and services, money, raw materials, labor, tools, and services the enterprise uses.
Economic Agent is an individual or organization capable of having control over economic resources, and transferring or receiving the control to or from other individuals or organizations. Examples of economic agents are customers, vendors, employees, and enterprises.
Economic Event represents either an increment or a decrement in the value of economic resources that are under the control of the enterprise. Some economic events occur instantaneously, such as sales of goods; some occur over time, such as rentals, labor acquisition, and provision and use of services. (http://reatechnology.com/)
How is the REA model of benefit to AIS designers and developers?
Relationships:
Cardinality - degree of maximum participation in a relationship
Optionality - (participation constraint) degree of minimum participation in a relationship
Relational Database Concepts and Definitions:
relation - (table for an entity) a set of data representing one or more occurrences of a resource, event or agent.
tuple - (row of a table) a set of data that describes a single instance.
attribute - (column or "field") a type of data that characterizes an entity.
referential integrity - for every attribute value in a relation that references another relation, the referenced row must remain intact.
Mapping the REA model to a Relational Database (discuss the steps):
Mapping the REA model to a Relational Database (discuss the steps):
1. Create a separate relational table for each entity: the logical starting point - specify the database schema before expansion of the relation to account for specific tuples. Steps 2 and 3 are needed to complete the schema2. Determine primary key: uniquely identifies any row within the table.
3. Determine the attributes for each of the entities
4. Implement the relationships among the entities by ensuring that the primary key in one table also exists as an attribute in every table for which there is a relationship specified in the REA diagram: referential integrity must be considered in this step. One to one relationships may start at either table. Many to many relationships must implemented by starting with a primary key that is a composite of the primary keys of the relations that are being linked. One to many relationships are implemented by including the primary key of the table on the one side of the relationship as an attribute in the table on the many side of the relationship.
5. Determine the attributes, if any, for each of the relationship tables.